What's the thinnest tire I can fit on a 622 x 18 rim?
I bought a Specialized Sirrus w/Alex Rims that say 622 x 18 but I can't pull the rim specs anywhere online and it came with 32mm tires. After a couple flats I'm thinking of picking up some Conti Gatorskins. Since I've been spending 80% of my time on paved roads and 20% on crushed limestone I think I can go thinner.
I originally wanted to outfit it with 28mm tires but am wondering if I can comfortably ride 25mm's?
I can't speak for those specific rims, but in general the rated capacities are wildly conservative. I used to fool around with tires a lot on my Atlantis, and I've run tires from 19mm to 41mm on the same wheels.
I wouldn't use 25mm tires on anything (I weigh 240), but I'm sure they'll fit your wheels.